Improvement in truss-bridges



J. M.. MCDONALD.

muss-BRIDGE.

4No.173,863.' Patented-renza,1876..

' :ummm

NY PETERS, PNOTDLITMDGRAPHER WASHINGTON, D. C.

UNITED STATES PATENT OFFLLCE. N

JOSEPH M. MeDoNALD, or 'roMLn \tS A)N, ARKANSAS.

IMPROVMENT IN TRUSS-BRIDGES.

Specification forming part of Letters Patent No. 173,863, dated February 22, 1876; application filed December 11, 1875.

'rescnts a'plan view, Fig. 2 a Side elevation,

and Fig. 3 a vertical transverse section, of my improved bridge on the line c c, Fig. 2.V

Similar letters ot' reference indicate corresponding parts. l y

My invention relates to an improved bridge construction, for larger and smaller spans, to be made of wood or iron; and consists, mainly, in the construction of an arch made of laterally braced and bolted pieces otalternately interlocking timber, in combination with braced and longitudinally connected side andintermediate trusses.

. In the drawing, A represents the central arched part of my improved bridge, which is constructed ot' pieces of timber ot' Suitable length, which are either set on edge, and brought in contact with each other, making a solid foundation, or two or more pieces may be lapped at the ends, and arranged to leave a space of suitable width between each set ot' timbers, the whole being laterally bound together by iron bolts at intermediate points.

The adjoining timbersB ot' each set or pair are so arranged that the joint ot' two pieces is centrally between the joints ot' the adjoining pieces, so as to alternate therewith, and form with the lateral crosspieces C, passing between the center of one piece and the joint of the adjoining piece, a ri gidly-interlocking arch of considerable strength, which, with suitable flooring, &c., may be employed as a separate structure, ifdesired.

The ends of the arch-timbers are seated into wooden oriron shoes D, secured to the abutments or piers, andthe liooring and railing of the bridge placed on vertical supporting-posts E, attached to the cross-pieces ot' the arch.

The arch-timbers may be doubled, trebled, Ste., by placing one arch on the other, for bridges with larger spans and :increased strength. At both sides, and, if desired, in the center ot' the arch A, are trusses F, that are made of vertical posts a, brace-pieces b, and longitudinaltop, intermediate and bottom timbers d, which are properly bolted together. The trusses F are attached to the central and terminal cross-pieces of the arch by which the connection ot' the arch and trusses,'and"at the same time the Vseparate working ot' each part, is obtained. pieces ofthe trusses, iron rods may be employed, which are looped on tenons of the lower 'ends ot' the posts. The posts are Steadied by cross-ties at the top and bottom, it' additional stiffness is required. The bridge forms by the arch and truss connection a compound structure of great strength, which is at the same time of simple, durable, and economical construction.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- The combination, of arch A, timbers B, cross -pieces C, shoes D, supports E, and trusses a b d F, all constructed and arranged as shown and described, for the purpose specitied.

JOSEPH M. MGDONALD.

Witnesses:

M. S. WILcoX, DANL. HOGAN.

In place of` the bottom 

